Engine



Aug. 11, 1959 Y D. BURcH 1 l2,898,898

ENGINE Filed Dec. 17, 1953 :s sheets-sheet-l ATTORNY Aug. 11,v 1.959 L. D. BURCH ENGINE 3 Sheets-Sheet 2 Filed Dec. 17, 1953 L. D. BURCH Aug. 11, 1959 ENGINE 3 Sheets-Sheet 5 Filed Dec, 1v. 1953 ATTORNEY United States Patent ENGINE Lewis D. Burch, Dearborn, Mich., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware l Application December 17, '1953, Serial No. 398,758

2 Claims. (Cl. 12S-'52) The present invention relates to engines and more particularly to spark ignited internal combustion engines.

In order to obtain the maximum eiciency from an internal combustion engine, it is desirable to utilize as high a compression ratio as possible. However when the gaseous charge in a cylinder is highly compressed, the temperature of the confined gases is greatly increased. In addition, during the initial burning of the explosive charge and the expansion thereof, the unburned end gases will be compressed thus further increasing the temperature of the end gases. As the temperature of the remaining charge approaches the kindling point of the gases, pre-ignition and detonation frequently occur. These phenomena not only decrease the efficiency but are structurally detrimental to the engine. the tendency toward detonation and pre-ignition it has been the practice to employ combustion chambers which include a compact iiring zone and a quench zone having a relatively large surface-to-volume ratio. In combustion chambers of this design the large amount of surface area will cool the end gases sufficiently to keep the temperature below the kindling point and thus prevent` detonation and/ or pre-ignition. In the past, these chambers have been more or less unsymmetrical with the llame front originating on one side of the chamber and traveling toward the other side.V This Vfrequently causes the flame front to reach one side of the cylinder before `it reaches the other side, This nonsymmetrical burning produces unbalanced forces on the face of the piston which tend to cause the axis ofthe piston to be misaligned with respect to the axis of the cylinder.

It is proposed to provide a combustion chamber which will produce a balanced resultant force on the face of the piston. This is to be accomplished by providing a combustion chamber having a spark plug disposed in substantial alignment with the axis of the cylinder. A compact firing zone is disposed symmetrically about the spark plug while an annular quench zone is disposed symmetrically about the firing zone. This objective may` be easily obtained by employing a combustion chamber l 55 which is defined by true surfaces of revolution disposed symmetrically about the axis of the cylinder. If the spark plug is positioned on this axis and the flame front travels at the same speed in all directions, the flame front will reach all portions of the periphery of the ring zone at substantially the same time; Also the ame front will reach all portions of the periphery of the annular quench zone simultaneously. Thus the flame front will always be symmetrically disposed about the axis of the cylinder and accordingly the forces on' the face of the piston will be substantially balanced at all times. This symmetrical annular quench zone will also have the additional advantage that a large volume of'end gases may be burned in the quench zone while still maintaining the advantages of a short flame travel in the quench zone. It is thus possible to obtain any desired propor-v tion between the volumes of 4the quench zone and the In order to reducey o firing zone without producing excessively long llame travel.

. It is also proposed to position the annular quench zone so as to provide a squish zone that will direct a ow of turbulent gases along the walls of the combustion chamber. By employing a symmetrical annular squish zone, the gases will flow radially inwardly toward the electrodes of the spark plug at a substantially uniform rate in all portions of the combustion chamber. This ow will not only provide a thorough scrubbing of the walls and valves but it will also provide the maximum amount of turbulence in the combustion chamber and thereby insure a complete mixing of the liquid fuel particles with the air without the disadvantages of preheating the charge.

t In a symmetrical combustion chamber it is possible to have a very compact firing zone and a very large quench zone. This permits the intake and exhaust valves to be disposed symmetrically about the spark plug on opposite sides thereof. Since it is no longer necessary Vto have both the intake and exhaust` valves disposed on the same sides of the combustion chamber, they may Abe placed on the opposite sides and made considerably larger than has been possible heretofore. Thus for any given size of combustion chamber, it is now possible to employ larger valves without interfering with` the engine operation.

It should be noted that if the valves ,are disposed `on the opposite sides of the combustionchamber, it is possible to position the intake and exhaust valves adjacent the opposite sides of the cylinder head. This in turn will permit the intake and vexhaust passages that interconnect the valve seats with the manifolds to be as short as possible and also as straight as possible. v l

:In order for the piston of a reciprocating engine to.. move freely in the cylinder of the engine, it is necessary to have a certain amount of clearance between the pis-Y ton and the walls of the cylinder. Due to this clearance and the fact that the piston drives a rotatingcrankshaft by means of a reciprocating connecting rod, there is a tendency for the axis Vof the piston to become misalgned withV respect to the axis of the cylinder. The forces produced by the movement of the piston and connecting rod and any unbalanced forces caused by the non-symmetrical burning of thegases in the combustion chamber will contribute to` the axis mis'alignment of the piston. Movement of the piston into and out of alignment causes so-called piston slap.V The slap not only causes objectionable noises but also produces excessive wear on certain portions of the cylinder Walls and the` piston.`

fIt is proposed to attach the connecting rod to the piston so the forces applied to the piston willV tend to produce a righting couple that will provide a more nearly balanced piston assembly. This is to be accomplished'byf attaching the connecting rod to the piston by meanswofY a wrist pin located between the piston rings and the face of the piston.

with or even below the axis of the Wrist pin.

As an engine is placed in operation, the temperature of the piston will rise. This will cause the piston to slap when the piston is cold, the'piston skirt is made elliptical with the major diameter normal to thefaxis of f' the wrist pin and Vsubstantially equal to the diameter?Y The pistonis constructediso that the;`

of thev cylinder. skirt will expand only along the minor diameter until Patented Aug. 11, 1959V This will tend to place the center" of the resultant forces on the piston either coincident -the skirt 'becomes roundand lits the cylinder at all wrist p in will prevent piston slap in one directionfand.

onlythe .bolttornv of..I the skirt willy prevent slap. inA the direction normal thereto.' l K ItisV proposed `to utilize a pistonA having. a surface. of. revolutionon theendfthereof. It. willthus bepossible. tmakethe crosssection ofthe piston elliptical=overfits en.- tire length so thatwhenit`beco'mes hotitwill have a circular shape. This will allow theentire. length of evena cold piston-to engage the cylinderwalls andr'educepistonf slap.

"By employinga piston in. which the wrist pin is. disposed abv'ev'theT rings and` the entire length of the skirt engages the cylinderwall, it will be. possibleltol decrease the overall` length of the piston. shortening.. the skirt in-this manner in`combination with the-wrist. pin being disposed above the piston rings will. permit. theuse of a very shortpiston. This will not only decrease the weight ofthe piston. butit will` also'permit the use of a much shorter cylinderA which in-turnV allows a material decrease inthe. size ofthe engine withoutdecreasing. the piston stroke.

In-l V-type engines and particularly V-eight engines the `intake manifolds. employ a4 pairfof. main distribution passages that. receive the'combustible. mixture. discharged from the carburetor. AEach. end of:a distribution passage communicates with a branch passage which has the op.- posite endsthereofadapted-todscharge thecombustible mixture into an intake portforone ofthe. cylinders. In. order to obtain the desired distribution offfuel charges into the various cylinders, the passages in themanifold are disposed in a criss-crossing..relationship. This prevents any of the passages beingfdisposedin a plane. and. necessitates that portionsl thereof. be located one above the other. This results in a complex structure. and in orderto mass produce suchf a manifold-itmust-of necessitybe a heavy casting. Also due to the necessarydisf position of the passages itis'extremely difficult, ifnot im. possible, for all of the passages to be of identical dimensions. A

I't is proposed to provide an intake manifold. of-the flat orfplanartypein which the various passages inthe manifold; may be disposed in the same general level without anyof-the passages crossing eachother. This will per, mit a simple structure which may be. either alight weight. casting or` inexpensively fabricated from sheet metal. This is to be accomplished by employing a plurality. of distribution passages that., extend. outwardly from a common. distribution chamber so asto communicatev withthe centers4 of branch -passages that have. the opposite. ends thereof in communication with the intake ports for. the cylinders. The distribution passages which. aredisposed in side. byside relationship. andA not in criss-cross relationship. may be of substantiallyidentical dimensionsso asto insureA uniform charges'being delivered to. all of.. the cylinders.

At the present time. V-type. engines. are. provided with a separate head foreach bank of: cylinders and a separate intake manifold which. in the case of` valve-in-head. engines is connected between theheads. Due to the necessityfor. employing heavy` castings for. the present intake manifolds, it is impractical to combine the heads andV manifold. However, using thesimplied intake manifolds ingdescribed above will permit the heads andmanifold to be combined intoan integral structure. Amongother advantages of. this arrangement will be the eliminationof thecarn shaft gallery cover and numerous gaskets, etc.

Since the heat rejectionfromthe engine to thecooling water.. determines the size oflthe cooling system, it is. del

sirable to provide lcooling for. thefminimumnumber of.

parts inan engine. Accordingly, itis proposed to. pro.-

vide a head in which it is necessary to provide only a minimum amountofcooling for the walls of-the combustionfchamber and the area around the intake and exhaust valve seats. By employing a head embodying the previously described combustion chamber with its large amount of quench area, the necessity for cooling of the Walls of the combustionI4 chamber is greatly decreased. By cooling the area around the valve seats, the valves A will remain at satisfactory operating temperatures. Since complishedby placing the exhaust valve seat adjacent the outboard edge offt'liehead. Thuszby placing the exhaust valve stem at theproper angle, itis possible to provide a straight exhaust passage from the valve seat to the exhaust port in the side of the head. Since the valve seat and ex- A haust portare as close together as possible anda straight passage is employed, the`amount of travelofthe hot 'ex-y haust gases' through'` the headis a minimum distance. Thus the heat-transfer to the head is reduced to a negligible amount andit is possible to eliminate useless cooling ofthe exhaust gases without a detrimental effect on the' engine operating temperature. This will4 permit a. materialI decrease inthe volume of: cooling water and=the size ofn thel attendantcooling jacket andradiator. Also. since the head. embodies the above described turbulent` combustion chamber, there will be a complete mixing of. the liquid fuel particles in the combustiblecharge'and, accordingly, it-will not be necessary to rely on heating of.V the intake passages. This will eliminatethe necessityof.. a cooling jacket about the yintakepassagesthus permitting further reductions inthe volume of cooling water.

These andfvother objects and advantages. of -the present invention will' become more fully. apparent as the der scrlption progresses. i

Referring to the: drawings.' Fig. l is. a side elevationalzview ofan engine employ ingth'e present invention.

Fig. 2-is a planview taken substantially along the plane. of-line Z-Zof Fig. 1V showing an intake. manifold for thev englne. Fig. Bis a cross sectional view taken substantially along` the planeof line S-BofFigl '1. T

4` isa plan viewtaken substantially along the plane of:l1n`e,4.-4 of Eig. 8 and showinga piston forthe engine.

Fig. 5 is a schematic. representation ofva crankshaft. suitable for,use in the present engine. Fig. 6I isa crosssectional viewofthe piston taken. substantially alongtheplane ofline 6;-6- ofFig. Sand, showing oneform ofiawrist pin.

Fig. 7e is anrexplodedperspective view.of=the wristpin.` assembly.of.Fig. 6. i

Fig. 8:. is anenlarged view-of the piston andvalve, as! semblyof Fig. 3, Referring. to the-drawings; in. more detail, the present-A inventionl may. beY embodied in.` any suitable engine 10; Inthe present. instance the engine 10 is of the solcalled V-type having two banks.1 2and1`4 of V aligned cylinders 1, 2, 3] 4,5, 6, 7 andh8, the axes of which are downwardly convergent toward-the bottom ofthe block 16; Each setl of. cylinders extends diagonally through the block 1610.

aereas" enclose the crankshaft 24 and form a sump for the engine lubricating oils.

A piston 32 of any suitable design may be provided in each of the cylinders for reciprocating movement therein. In the present instance each of these pistons 32 includes a cylindrical skirt 34 and a convex face 36 on the upper end thereof. Since there is a clearance between the skirt 34 and the cylinder walls 38 so as to permit free reciprocating movement of the piston 32, sealing means may be provided to prevent the passage of gases between the skirt 34 and the cylinder walls 38. This sealing means may include a plurality of annular grooves 40 in the skirt 34 adapted to receive resilient piston rings 42 for sliding engagement with the cylinder walls 38.

The convex face 36 on the upper end of the piston 32 forms one wall of the combustion chamber 44 and, accordingly, the shape of this surface will be determined by the design of the combustion chamber. In the present instance, this face is a dome 46 forming a convex surface of revolution, the details of which will be described in connection with the combustion chamber.

Each reciprocating piston 32 is drivingly coupled to a throw 47, 48, 49 or 50 on the crankshaft 24 by means of a suitable connecting rod 51, 52, 53, 54, 55, 56, 57 or 58. The lower end of each of the connecting rods may be provided with a bearing suitable for attachment to one of the throws of the crankshaft 24. The upper end of each of the rods are provided with bearing means 59 for connecting it to the inside of the piston 32. If the connecting rod is attached to the piston 32 above the resultant of the forces acting on the piston 32, there will be a righting couple that will tend to maintain the piston axis in substantial alignment with the cylinder axis. Therefore, in order to provide a more balanced piston assembly, the connecting rod is preferably attached to the piston 32 as close as possible to the face 36 of the piston 32. A wrist pin 60 is mounted inside of the piston 32 to receive the bearing 59 in the upper end of the connecting rod. The axis of the wrist pin is preferably disposed between the upper end of the piston 32 and the piston rings 42.

` Although the wrist pin 60 may be mounted on the piston 32 in any suitable manner, it should be noted that the conventional open ended, hollow wrist pin driven through the sides of the piston is not suitable because the piston rings cannot be relied upon to seal the pin from the gas pressures developed in the combustion chamber. In order to support the pin 60 a web 61 may be provided inside of the dome 46. The web 61 is adapted to t into grooves 62 provided on the opposite ends of the wrist pin 60. The wrist pin 60 may be secured to this web 61 by any suitable means such as the screws 62' and nuts 63. In order to allow for differences in the amount of thermal expansion and contraction between the web 61 and pin 60, the screws 62 may have a square shank 64 that tits inside of the rectangular opening 65 in the web 61. The lower edge of the web 61 may be notched at 68 to provide clearance for the enlarged upper end of the connecting rod when it isV secured to the wrist pin 60.

Since the piston 32 is free to pivot about the axis of the pin 60, the axis of the piston 32 may become misaligned with respect to the axis of the cylinder. Movement of the piston 32 into and out of alignment will produce so-called piston slap which produces undesirable noises and undue wear on the cylinder walls 38. To prevent piston slap the outside diameter of the skirt 34 normal to the axis of the pin 60 is substantially identical to the diameter of the cylinder. Thus the skirt 34 will slidably engage the walls 38 of the cylinder and reduce the tendency to slap. Since the bearing 59 in the upper end of the connecting rod is a snug fit on the wrist pin 60, there will be no relative movement between the rod and the piston 32 about an axis normal to the axis of the pin 60. Therefore even though there is a limited clearance between the cylinder walls 38 and the piston skirt 34 on a diameter parallel to the pin 60, there will be nol If this diameter is madev slightly under size as the piston 32 becomes hot during' use, the thermal expansion of the web 61 will force the' piston slap in this direction.

piston 32 into a round shape so that the skirt 34 will then engage the cylinder walls 38. As the piston 32 becomes heated the web 61 will expand. This will stretch the piston so as to increase the minor diameter and decrease the major diameter. If the proportions are properly chosen, the decrease in the major diameter will equal the increase due to expansion of the piston and the fully expanded web 61 will make the minor diameter equal the major diameter. It should be noted that the face 36 may be made elliptical similar to the skirt 34 because the piston 32 does not have the usual planar face. Thus the entire length of the skirt will lit the cylinder whether it is hot or cold. Since there will be an increase in the bearing area, the length of the piston may be greatly decreased. Thus there will be no piston slap whether the piston is hot or cold and yet, there will be room for thermal expansion as the piston 32 warms up.

In order to close the upper end of the cylinder and thus form a combustion chamber 44, a head 70 may be provided for each bank of cylinders 12 and 14. The heads 70 which are adapted to be secured to the planar faces 20 and 22 on the block 16 have cavities 72 formed therein to register with the openings 18 formed by the cylinders. The walls 74 of this cavity 72 cooperate with the surface of the face 36 on the piston 32 to dene the shape of the combustion chamber 44.

In order to provide a symmetrical combustion chamber such as previously described, the surface 74 of this cavity 72 is preferably a concave surface of revolution developed about the axis of the cylinder. Although any surface may be used, a substantially hemispherical cavity is shown. The domed face 36 on the piston 32 is provided with a convex surface 76 of revolution which is developed about the axis of the cylinder to be substantially coaxial with the concave surface 74 in the head 70.

A spark plug 84 may be mounted in the head 70 so` that the electrodes 86 thereof project into the tiring zone.

82 substantially on the axis of revolution. The depressed center is preferably positioned so that the advancing ame front will strike the center of the surface 80 rst and rapidly progress outwardly toward the rim 88 of the firing zone 82. Since the distance from the electrodes 86 to the rim 88 is substantially uniform in all directions, the ame front will reach all parts of the rim 38 simultaneously. Such a compact firing zone 82 will allow a very rapid initial burning of the major portion of the combustible charge without the detonation of any pockets of unburned gases trapped in the ring zone 82.

The peripheral portion 78 of the dome 86 is a portion of a convex spherical surface that closely approaches the periphery of the hemispherical cavity 72 when the piston 32 is at top dead center. These two closely spaced surfaces form an annular quench zone 90 symmetrically' though the end gases are highly compressed, their temi- 11er-stateswillI be maintained below` the kinuiirtgfpoint. so.T as to'fprevent d etonation. By employing an annularr quenchzone, 911 with the amefront` traveling radially a` uniform distance, iuall Vdirections the marsrourn amount. of end gases may behurned in thel minimum amount' of time. allows full. advantage to beY taken,y of the attenante.

By vemploying an entirely symmetrical combustion` charnher, 4fifthe'forces, produced on vthe face 36` of the pistof'z will be balanced. Thus the tendency to causel rni'salignment of the pistonZ andother troubles present in",unhalancedpistonassemblies will be greatly reduced orenti'rely eliminated.

uItshouldalso be. pointed outthat as. the piston 32 .vtra v els Maruti/[through tbe'fey'liuuertbe gases trapped, in tbe. qiiiench hzone'f90fwill be compressed faster thanithe: @$6.5 iriithe iiringzonev, 8&2, particularly when; theupiston 32 ap-4 proac de'ad center. This'will result in thelquench zgne acting asY asquidsh zone 92 that will force thegas'es. toow. radially inwardly alongthe wallsof the combustion chamber 44 towards the eletrodes 86,., of the spark plus. 84.- 1Tbe. flow of gases alot-ts tbese. Walls. witllnrotuee a; scouring action Wbieh-Willteudfto remove. Carbon ano other deposits from the valves 94 and 916', walls 74. and eleotrodes 86.- Inadditionrtbs. violent. now ofsases-wll produce. aturbulent aotionwbiob Witttborougbly trtr'ttbe. liquidA fuel. particles andan, in. tbe.- oornbustible, ebarsel( 1biswillinsure a. more oomnleteburnirrs of .the fusti vf tlthonsh.the intake 94. and-exhaust vali/esito.. may. be. positioned in any portion of thecombustionlchamber 4de'y itfhas-.been found to be advantaseousto positiontbervah/e seats 9.8 and 1.00 symmetrically aboutrtlre axiaofra/Olu: tion In order toallow more eoient.. nralrifoldus, itis; also desirable to place. theerthaust valve. seatltltiontbe. ontboardside. and the intake ,valve seat. ott the. iuboartr side of. the., heads 70.-. Theintake. and ertbaustY valveiar1 d,9v6;t in their respective seats 98land1- 10Q with their. stems,1vv2 and 103 projecting outwardly, into; theV valve guides1044for slidingmovement therein. Thepush rodsI 10.6 rand 1 0 7y and rocker armsr1`08 and 1(191 are actuated by. a, camshaft 110l which isdriven by the crankshaft24- to .insure opening of thevalves 9 4and 9.6at thercorrect-V time. stems 102 to oppose the push rodsr106 Vandbias the valves into the. closed. position. Although the push rods 1.0.7

are shown. as being horizontally disposed between the,

diameters of the cylinders, it should be understood that.y thelength of the engine may be decreased bYmovingthe push rods 107 so that theyextend above the diameters of, the cylinders. This may be.accomplished by raising the cam. shaft 110 or by inclining the push.rods.1i)7 so *that* theouter end of therods will be above the cylinders. This will necessitate incliningtherocker arrns 1.09.

An exhaust port 114 is provided in the side of-the head. 70 adjacent each exhaust valve seat 100 and is connected thereto byl a short straight exhaustpassage.116;thatdis1I charges directly into the exhaust manifold 118. It isde:Y sirable that the length of this passage 116; be as shortas. possible to reduce theamount of. heat transferred from. the hotexhaust gases to the head 70. Ifthe valve stern 103 is placed atan angle to the exhaust passage 116, the passage may be straight between the valve. seat 100 and part 114.

The intake manifold 120 is aat or planartype. That is, thecorresponding partsof -each distribution passage are .preferably disposed at thesamengeneral elevation and no distribution passage Crosses another distribution Pas.:-

sage. It should be understood thatlalthough the present`V manifold is substantially av planelthe.. manifold may be. shaped similar to Aa y cylinderor t some other suitable. formV toaeoommodato itafttitlg outnthoeglte 0.1 fot anyA other. reason. ft desired, thet heads. 701tmay bemade Vintegral with .Athemanifold 120 in the form of inclined: edge portions. `The Center offtbetoaoifold .may Vbe Provided. with Coil springs4 112, are disposed about the valve.

. manifold lznimrnsdately beiow'tnetrange 12.2, The in:

terior of the distribution chamber 128 is intercgnnected tothe centers of the branch passages 130, 132, 1 34 and 16.by meansof distribution passagesl, 140 142r andy 144, that extends. outwardly from the chamber 1,23.M The 5, branch passages 130, 132,134A and 136 extendlongitudinally ofthe manifold so that theleopposite ends there-l of` communicatef with the intake valves 9,4of adjacent cyl.- inders. Thev distributionpassages,13&,v140, 142ar1dl 144. may extend outwardly from the'distributioncharriber 142.8, in any suitable manner, however, inthe presentv instance the. distribution passagesare disposed. side: by side soas to'extend transversely ofg the manifold 120 from1 theopf. positesides thereof. v It shouldbenotedthat the passages 1,38, 140, 1 42 and 1.4.4,are separated merelybypartitions 145 and147` Since eachdistributionpassage is'disp'osed4 entirely on its own side of, thel partition, thek passages do. not. have to be inA criss-crossing,relationship. This per# mits,thepassages.v 138, 14,0, 142 andv 1.454` to be disposed., in substantially the same plane or 'generallevelxandtheren byelir'ninates.. the nefces'sityfforV a bulky and heavy manifold. Thu/s themanifold 1201I`f1tybe asimplelightweiglit. casting or fabricated from sheetmetal.

In order to insure eachcylinder obtaining ai substan..

tialv itientioalrobargertbe dist,.r'tbutionpassages.138;'1510,`

1.4.2ar1t1 14.4 may. be substantially,identical.' so. that 'thereL4 that are nreferablyvdisnosedatrisbtansleslto'eaobothen The. Vtransvorse-.portions 14.6J 145;. 1.5ttfand. 1.521 areloon. netted to the opposite. sioes..o.t.tbe. Chamber. 1.28 and 'extend.- across. the manifoldlltberefrom, The Partitions., 1.4.5. and 14'/` that separatetbe transyerseportions, alterni. up to the sides'. of the chamber 128. Thuslthere will began.. unrestricted passage between all of the distribution sages which will p.e.rtni.t.the.oorr.rbust.ib1e Charte.v to; Lbe drawn. from anyportiou. ofthe-.Chambon Thusfth Sharan forany one cylinder, may bedrawntromalhfour; barrelsi ofthe carburetor. The lonsitnttirral portions .15.4. 1.56.15@l and-1.60 preferably have; the innerfenositbereof Connected. at right angles to the outer endsofthegtrarrsyersepomme; 14.6., 148. and.. 152.` andthe outer ends tbereotf Cour. nected to the centers of thebranch passages130, 1312,V A13515 and 136. It, is apparent thatltheorrrbustible chargefor-E any Cylinder witlalways travelthrougb adistribtttion.iras.:.r sageand halfof a branch, passage.V

In order. to. provide the:maximum volurrretrideiciency,l it is. desirable. that. the; combustible charges jggvviirgZ through eachdistribution passage beispaced avt st Jbstari-x tially uniformrtime increments.V Thusgin a.teurcyclefV` eighty engine, the charge ineeachy distribution passage is,- preferably spaced at 3,6u0v intervals,l Thereare nunvrerousy means for. obtainingaring order thatwillprodu'ce this distribution of owinthe manifold. It;has beenfound that aplanar crankshaftZflgin whichall of the pistonslin each setoffour. end cylinders `move together. Arturo/ throw crankshaft may be employed in which four-pieten rods will 4becOnneCted .to eachthrow, Thisin etetwwili amountv to two crankshafts each of which may besepe?. ratelybalanced by suitable,counterweights. A )gilarrarl fourthrow crankshaft 24 such asshown in Fig:y SgnayA also beemployed.` The crankshaft 24;.is rotatablysupf. ported by a front mainbearing.162, atrear, mair1,bearf. ing 1641-,y andt three intermediate main bearingsl.' The,y front throw or number one throw 4T may be connected- -to thepistonsdin'cylinders 1- and5-by means of connecting rods 51 and 55: The second forward'throw ornurnber tvv,othrow.48rwhichisconnected to cylinders 2^andl6 by*A connecting rods 52 and 56 may be disposed in the same plane as the forward throw 47 and on the sarne side of the axis of the crankshaft 24. The rear throw or number four throw 50 and the throw 49 immediately in front thereof or number three `throw which are connected to cylinders 4 and 8 and cylinders 3 and 7, respectively, by connecting rods 54, S8, 53 and 57 may be in the same plane as the two forward throws 47 and 48 but disposed on the opposite sides of the crankshaft. Thus the throws 47 and 48 will be 180 out of phase with the throws 49 and S0. 1n order to prevent engine vibrations, it may be desirable to balance the crankshaft 24. The two intermediate throws 48 and 49 will be disposed on the opposite sides of the crankshaft 24 so that they will tend to balance each other. However, the number one throw 47 and the number four throw 50 may be provided with counterweights 167 that Will tend to maintain the crankshaft 24 balanced at all times.

If the cylinders are numbered 1 through 8 starting at -the left front cylinder and proceeding towards the rear and then continuing with the right front and proceeding towards the right rear, a ring order of l, 8, 4, 5, 2, 7, 3, 6 will produce tiring impulses equal spaced at 90 for clockwise rotation when viewed from the front of the engine. When such a firing order is employed the cornbustible charge for cylinder 1 will be drawn through distribution passage 142 rst. 90 later the charge for cylinder 8 will be drawn through distribution passage 140. Following this at equally spaced 90 intervals the charges for cylinders 4 and 5 will be drawn through distribution passage 144 and 138, respectively. Thus during one revolution of the engine each distribution passage has conducted one combustible charge to a cylinder. As the next revolution begins, air will be drawn through distribution passage 142 for cylinder 2. It should be noted that this charge passes through distribution passage 142 360 after the charge for cylinder 1. Following this the charges for cylinders 7, 3 and 6 will pass through distribution passages 140, 144 and 138, respectively, at 90 intervals so as to be 360 behind the charges for cylinders 8, 4, and which pass through the same passages. It will thus be apparent that by employing this firing order the charges through the distribution passages 138, 140, 142 and 144 will always be evenly spaced so as to cause the minimum resistance to the ow of air therethrough.

In order to insure that the engine 10 operates at a satisfactory temperature, cooling means may be provided such as a water jacket 170 in the block 16 and an interconnected water jacket 172 in the head 70. The water jacket 170 in the block 16 surrounds each cylinder in heat exchanging relationship so as to keep the walls 38 thereof sufficiently cool. The water jacket 172 in the head 70 surrounds each valve seat 98 and 100 so as to insure the valves 94 and 96 remaining cool enough to prevent burning thereof. Also it may be desirable to place a portion of the water jacket 172 about the stem 102 of the exhaust valve 96 to prevent an undue accumulation of heat in the exhaust valve 96. However, since the length of the exhaust passage 116 in the head 70 is kept to a minimum, the heat transfer to the head 70 is a negligible amount and accordingly, there is preferably no heat transferred from the exhaust gases to the water jacket 172.

While the foregoing description and igures have been confined to one embodiment, it will be apparent to those skilled in the art that numerous modifications may be made without departing from the spirit thereof. Accordingly, it is to be understood that the foregoing is to be considered as illustrative only and in no way restrictive, reference being had to the appended claims to determine the scope of the invention.

What is claimed is:

1. In an intake manifold for an engine having a pair of angularly disposed banks of cylinders, a distributing chamber disposed in the center thereof to receive a combustible mixture of air and fuel from a plurality of charge forming passages, a plurality of branch passages extending longitudinally of said manifold along the opposite sides thereof to be substantially parallel to said banks, each of said branch passages having the opposite ends thereof formed for communicating with the intake means for said engine, a plurality of distribution passages, each of said distribution passages having a portion thereof disposed transversely of said manifold and a portion thereof disposed longitudinally of said manifold, the inner ends of said distribution passages communicating with said distribution chamber at substantially right angles to said charge forming passages and the outer ends communicating with the centers of said branch passages at substantially right angles thereto, the thickness of said manifold being substantially the same as the thickness of said passages.

2. An intake manifold for a multicylinder, internal combustion engine having a separate intake means for charging each of said cylinders and adapted to have a carburetor mounted on the top thereof with at least one downwardly directed charge forming passage, said intake manifold comprising separate branch passages extending longitudinally along the edges of said manifold, each of said branch passages having the opposite ends thereof adapted to communicate with adjacent pairs of said intake means, substantially identical passageways, each of which has a substantially straight transverse portion and a substantially straight longitudinal portion, the inner ends of said passageways being adapted to communicate with said charge forming passages and the outer ends thereof being adapted to communicate with the centers of said branch passages at substantially right angles, said passages and passageways being disposed substantially in a common plane.

References Cited in the le of this patent UNITED STATES PATENTS 1,012,635 Harmer Dec. 26, 1911 1,132,256 Gunn Mar. 16, 1915 1,212,478 Hall Jan. 16, 1917 1,250,426 Brush Dec. 18, 1917 1,261,530 Hickey Apr. 2, 1918 1,265,735 Brush May 14, 1918 1,285,129 Goodrich Nov. 19, 1918 1,365,564 Strickland Jan. 11, 1921 1,414,384 Tartrais May 2, 1922 1,548,382 Paul Aug. 4, 1925 1,617,986 Blank Feb. 15, 1927 1,659,659 McCuen Feb. 21, 1928 1,756,161 MacPherson Apr. 29, 1930 1,768,136 Moorhouse June 24, 1930 1,862,723 Summers June 14, 1932 1,942,227 Timian Jan. 2, 1934 2,035,264 Edwards Mar. 24, 1936 2,051,305 Le Valley et al. Aug. 18, 1936 2,082,869 Brown June 8, 1937 2,296,469 Kastler Sept. 22, 1942 2,334,146 Davies Nov. 9, 1943 2,523,611 Clayton Sept. 26, 1950 2,603,199 Moseley July 15, 1952 2,621,092 Clark Dec. 9, 1952 2,640,471 Haltenberger June 2, 1953 FOREIGN PATENTS 378,169 Germany July 4, 1923 635,111 France Dec. 17, 1927 265,940 Switzerland Apr. 1, 1950 

